Super Volcano Will Challenge Civilization, Geologists Warn

The eruption of a super volcano "sooner or later" will chill the planet and
threaten human civilization, British scientists warned Tuesday.

And now the bad news: There's not much anyone can do about it.

Several volcanoes around the world are capable of gigantic eruptions unlike
anything witnessed in recorded history, based on geologic evidence of past events,
the scientists said. Such eruptions would dwarf those of Mount St. Helens, Krakatoa,
Pinatubo and anything else going back dozens of millennia.

"Super-eruptions are up to hundreds of times larger than these," said
Stephen Self of the United Kingdom's (U.K.) Open University.

"An area the size of North America can be devastated, and pronounced deterioration
of global climate would be expected for a few years following the eruption,"
Self said. "They could result in the devastation of world agriculture, severe
disruption of food supplies, and mass starvation. These effects could be sufficiently
severe to threaten the fabric of civilization."

Self and his colleagues at the Geological Society of London presented their
report to the U.K. Government's Natural Hazard Working Group.

What's
in Store

The predicted
effect a super volcano at Yellowstone. Click
to enlarge.

Super
Evidence

In the Jemez Mountains, near Santa Fe, New Mexico, sits the
Valles Caldera -- the circular feature at left in this false-color
satellite image (vegetation is red). It's about 15 miles (24
kilometers) wide, made by two super-eruptions
1.6 and 1.1 million years ago.

The rocky
mound below, the result of the older eruption, is 820 feet(250 meters) thick.

Satellite
image: Landsat
Middle photo: S. Self

"Although very rare these events are inevitable, and at some point in the future
humans will be faced with dealing with and surviving a super eruption," Stephen
Sparks of the University of Bristol told LiveScience in advance of Tuesday's
announcement.

Supporting evidence

The warning is not new. Geologists in the United States detailed a similar
scenario in 2001, when they found evidence suggesting volcanic activity in Yellowstone
National Park will eventually lead to a colossal eruption. Half the United States
will be covered in ash up to 3 feet (1 meter) deep, according to a study published
in the journal Earth and Planetary Science Letters.

Explosions of this magnitude
"happen about every 600,000 years at Yellowstone," says Chuck Wicks of the U.S.
Geological Survey, who has studied the possibilities in separate work. "And
it's been about 620,000 years since the last super explosive eruption there."

A super eruption is a scaled up version of a typical volcanic outburst, Sparks
explained. Each is caused by a rising and growing chamber of hot molten rock
known as magma.

"In super eruptions the magma chamber is huge," Sparks said. The eruption is
rapid, occurring in a matter of days. "When the magma erupts the overlying rocks
collapse into the chamber, which has reduced its pressure due to the eruption.
The collapse forms the huge crater."

The eruption pumps dust and chemicals into the atmosphere for years, screening
the Sun and cooling the planet. Earth is plunged into a perpetual winter, some
models predict, causing plant and animal species disappear forever.

"The whole of a continent might be covered by ash, which might take many years
-- possibly decades -- to erode away and for vegetation to recover," Sparks
said.

Yellowstone may be winding down geologically, experts say. But they believe
it harbors at least one final punch. Globally, there are still plenty of possibilities
for super volcano eruptions, even as Earth quiets down over the long haul of
its 4.5-billion-year existence.

"The Earth is of course losing energy, but at a very slow rate, and the effects
are only really noticeable over billions rather than millions of years," Sparks
said.

Human impact

The odds of a globally destructive volcano explosion in any given century are
extremely low, and no scientist can say when the next one will occur. But the
chances are five to 10 times greater than a globally destructive asteroid impact,
according to the new British report.

The next super eruption, whenever it occurs, might not be the first one humans
have dealt with.

About 74,000 years ago, in what is now Sumatra, a volcano called Toba blew
with a force estimated at 10,000 times that of Mount St. Helens. Ash darkened
the sky all around the planet. Temperatures plummeted by up to 21 degrees at
higher latitudes, according to research by Michael Rampino, a biologist and
geologist at New York University.

Rampino has estimated three-quarters of the plant species in the Northern Hemisphere
perished.

Stanley Ambrose, an anthropologist at the University of Illinois, suggested in 1998 that Rampino's work might explain a curious bottleneck in human evolution: The blueprints of life for all humans -- DNA -- are remarkably similar given that our species branched off from the rest of the primate family tree a few million years ago.

Ambrose has said early humans were perhaps pushed to the edge of extinction after the Toba eruption -- around the same time folks got serious about art and tool making. Perhaps only a few thousand survived. Humans today would all be descended from these few, and in terms of the genetic code, not a whole lot would change in 74,000 years.

Sitting ducks

Based on the latest evidence, eruptions the size of the giant Yellowstone and
Toba events occur at least every 100,000 years, Sparks said, "and it could be
as high as every 50,000 years. There are smaller but nevertheless huge eruptions
which would have continental to global consequences every 5,000 years or so."

Unlike other threats to mankind -- asteroids, nuclear attacks and global warming
to name a few -- there's little to be done about a super volcano.

"While it may in future be possible to deflect asteroids or somehow avoid their
impact, even science fiction cannot produce a credible mechanism for averting
a super eruption," the new report states. "No strategies can be envisaged for
reducing the power of major volcanic eruptions."

The Geological Society of London has issued similar warnings going back to
2000. The scientists this week called for more funding to investigate further
the history of super eruptions and their likely effects on the planet and on
modern society.

"Sooner or later a super eruption will happen on Earth and this issue also
demands serious attention," the report concludes.

Robert Roy Britt

Rob was a writer and editor at Space.com starting in 1999. He served as managing editor of Live Science at its launch in 2004. He is now Chief Content Officer overseeing media properties for the sites’ parent company, Purch. Prior to joining the company, Rob was an editor at The Star-Ledger in New Jersey, and in 1998 he was founder and editor of the science news website ExploreZone. He has a journalism degree from Humboldt State University in California.